The present invention relates to a gas mixing devices in general and more particularly to improved apparatus for calibrating gas analyzers comprised of a plurality of critical nozzles which have their outputs connected to a mixing chamber.
Known gas mixing devices, also called gas distributors, use eleven or eight critical nozzles to obtain eleven or seventeen different concentrations or selectively variable proportions. At a specific input gas pressure, because of a special shaping of their outlet ports, these nozzles provide a constant gas passage that remains dependent only on the opening cross-section. Nozzles of this type require precision manufacturing and exact measuring.
Because of this last requirement there is a need to increase the ratio between the number of selectively variable proportions and the number of critical nozzles required for this purpose, so that one can make do with a smaller number of critical nozzles.